Michael Bourn is a better leadoff hitter than you probably think. But …

If Michael Bourn’s ability to bat leadoff is the biggest problem the Astros have, then get your bets down on Brad Mills for 2011 Manager of the Year.

Bourn is a lot better in that role than Astros fans tend to think after watching him average .262 with 53 walks and 120 strikeouts the past three seasons.

We’ll get to the (potentially) bad news about Bourn later.

Make no mistake: Bourn is far from the perfect offensive player in general and leadoff hitter in particular. For a guy with a career slugging average of only .348, Bourn strikes out way too often. His offense and defense are almost totally dependent on his speed, and major-league players don’t get faster as they get older.

Bourn scored 97 runs two seasons ago when his on-base percentage was .354. His OBP fell off to .341 last season, and his runs total fell to 84. Clearly, it would behoove Bourn to get on base more often, which is as easily said – and difficultly done – as laying off that slider that dives into the dirt at the last instant.

Rickie Weeks

As tantalizing as it might be to wonder how much havoc could create if he could push his OBP to .360 or better, let’s deal with reality. Of the 15 National League Players who had at least 300 plate appearances in the leadoff spot last season, only three broke the .360 barrier: the Dodgers’ Rafael Furcal (.370), the Brewers’ Rickie Weeks (.363) and the Braves’ Martin Prado (.362). Bourn’s .342 OBP as a leadoff hitter was a respectable seventh, ahead of the likes of the Mets’ Jose Reyes (.332), the Phillies’ Jimmy Rollins (.322) and the Reds’ Brandon Phillips (.302).

The leadoff hitter’s primary job, plain and simple, is to score runs. The average NL leadoff hitter had a .323 OBP and scored a run every 7.43 plate appearances. Hitting atop the NL’s second-least productive batting order, Bourn scored once every 7.38 plate appearances. Bourn isn’t the next coming of Tim Raines, but he’s better than most leadoff hitters in the league and does create some havoc on the bases.

On top of stealing a league-leading 52 bases last season, Bourn was one of the best in the league at pure base running. According to the Retrosheet data from last season, Bourn took the extra base (first to third and second to home on singles, first to home on a double) on 61 percent of his opportunities last season. The league average: 40 percent. Those extra bases translate into extra runs. Bourn, for instance, scored from second on a single 16 of 20 times; the average player scores 12 times (59.4 percent) in those situations.

Bourn, 28, has won the Gold Glove as a center fielder the past two seasons. He avoided arbitration this off-season by signing a one-year, $4.4 million contract, and he’s clearly angling for a get-set-for-life payday. The hiring of Scott Boras raised some eyebrows, because it sent the signal that Bourn isn’t likely to offer his hometown team a discount if he gets to free agency after the 2012 season.

What is Bourne’s earning potential?

Juan Pierre has a .298 career average and has scored 100 or more runs three times.

He emerged from his age-27 season with a career .263 average, 173 stolen bases and an OPS+ of 83. (OPS+ is the on-base-plus slugging, adjusted for era and park effects. The league average is 100, with 110 being 10 percent above the norm and 90 being 10 percent below it). Juan Pierre had 267 steals and a career OPS+ of 87 after his age-27 season. He parlayed a .292 average, 204 hits and 58 steals at 28 into a five-year, $44-million contract with the Dodgers. Coming off a 2010 season in which he batted .275, stole an American League-leading 68 bases and posted a 78 OPS+ for the White Sox, Pierre will earn $8.5 million in the final year of that contract.

Pierre and Bourn, as it turns out, are two of 16 players in history to steal more than 150 bases while posting an OPS+ of lower than 100 through their age-27 season. They’re speed players, in other worlds, with below-average hitting skills. Studying those player types might give the Astros some useful guidance as to what kind of long-term commitment they might want to make with Bourn.

Six of the other 14 players had careers that continued for fewer than 1,500 more at-bats. Two others, Corey Patterson (703 at-bats since the age-27 season) and former Astro Willy Taveras (35) are well below the 1,500 at-bat threshold but still active. The biggest doomsday scenarios involved former Ranger Oddibe McDowell (183 career at-bats after 27), former Astro Gerald Young (60), Miguel Dilone (370) and Rudy Law (697).

The best-case scenarios? Willie Davis had 1,514 hits, 218 steals, three Gold Gloves, two All-Star game selections and a 110 OPS-plus after his age-27 season. Johnny Damon has 1,512 hits and counting, two All-Star appearances, two World Series rings and a 109 OPS+ since his age-27 season. Jose Cardenal banged out 960 hits, stole 198 bases, and had a 112 OPS+ after his age 27 season.

Of course, Davis, Damon and Cardenal also had better hitting credentials than Bourn at the same stage in their careers.

Washouts Young and Dilone had a career OPS+ of 83 – the same as Bourn – heading into their age-28 seasons. So did Patterson, who has batted .229 over his past 241 games. Vince Coleman had an OPS+ of 82 through 27 and 85 after it. Omar Moreno had an OPS+ of 81 through 27 and 76 after it.

Maybe Bourn can succeed where so many other slap-hitting speed merchants have failed. Maybe he bring along his offensive skills to the point they’ll compensate for the inevitable decline in his speed. If so, he’ll truly be a special, break-the-mold player.

SPEED MERCHANTS: Michael Bourn enters the 2011 season with a career .263 batting average, 173 stolen bases and a career adjusted on-base-plus-slugging of 83 (100 is the league average, with 110 being 10 percent better than the norm and 90 being 10 percent below the norm). Fifteen others have emerged from their age-27 season with more than a 150 steals with an OPS+ below 100. Here is how the careers of these speed-oriented players shook out:

PLAYER

G

AB

AVG

OBP

SLG

SB-CS

OPS+

Willie Davis, 1965-73

1058

3906

.268

.302

.400

180-66

99

Willie Davis after 27

1371

5617

.287

.318

.420

218-65

110

Johnny Damon, 1995-2001

958

4126

.286

.346

.425

183-54

97

Johnny Damon after 27*

1318

5920

.288

.362

.444

202-43

109

Oddibe McDowell, 1985-1990

771

2646

.252

.321

.401

155-51

96

Oddibe McDowell after 27

59

183

.262

.355

.317

14-2

76

Jose Cardenal, 1963-71

1018

3665

.260

.307

.376

196-73

95

Jose Cardenal after 27

999

3299

.291

.360

.416

133-64

112

Chad Curtis, 1992-1996

696

2567

.265

.343

.391

161-79

94

Chad Curtis after 27

508

1450

.263

.359

.405

51-19

98

Rudy Law, 1978-84

537

1724

.276

.328

.360

185-53

89

Rudy Law after 27

212

697

.260

.318

.380

43-12

88

Juan Pierre, 2000-05

845

3411

.305

.355

.375

267-96

87

Juan Pierre after 27*

748

2773

.289

.337

.355

260-77

82

Cory Patterson, 2000-07

856

3100

.258

.298

.414

168-41

83

Corey Patterson after 27*

241

703

.229

.267

.361

37-14

65

Miguel Dilone, 1974-82

591

1630

.272

.318

.339

215-69

83

Miguel Dilone after 27

209

370

.232

.302

.303

52-9

72

Gerald Young, 1987-92

605

1755

.246

.330

.302

153-71

83

Gerald Young after 27

35

60

.233

.313

.350

2-2

72

Vince Coleman, 1985-89

754

3038

.261

.323

.329

472-98

82

Vince Coleman after 27

617

2368

.267

.324

.364

280-79

85

Omar Moreno, 1975-80

683

2506

.254

.321

.344

313-97

81

Omar Moreno after 27

699

2486

.249

.290

.342

174-85

76

Brian Hunter, 1994-98

520

2124

.271

.316

.355

177-47

79

Brian Hunter after 27

480

1223

.250

.308

.330

83-14

61

Darren Lewis, 1990-95

579

2022

.249

.319

.314

151-61

75

Darren Lewis after 27

774

2059

.252

.327

.330

96-46

70

Willy Taveras, 2004-2009

643

2377

.276

.321

.328

194-42

68

Willy Taveras after 27*

27

35

.208

.243

.257

1-2

36

* — still active.

Vince Coleman, shown here on a 1985 Topps card, captured five of his six stolen-base crowns before his 28th birthday.

Oddibe McDowell, shown on his 1987 Topps card, looked like a star in the making, but his career fizzled.

Omar Moreno was the leadoff hitter on the Pirates' 1979 World Series-winning team, but his career ebbed as soon as his speed diminished.

• • •

Alan Trammell

Among those with Feb. 21 birthdays are former Astros pitcher Jack Billingham and former Tigers shortstop Alan Trammell.

Billingham, who had career record of 145-113, was part of the disastrous trade that also sent Joe Morgan, Cesar Geronimo and Ed Arbrister to the Cincinnati Reds in return for Lee May, Tommy Helms and Jimmy Stewart. In 1973-74, Billingham went 19-10 and 19-11 and finished in the top six of the Cy Young Award voting both seasons.

Trammell made six All-Star teams, batted .285, lashed 2,365 hits and won four Gold Gloves. He batted .314 on the Detroit Tigers’ 1984 World Series-winning team and was second in the American League Most Valuable Player voting in 1987 (.343, 28 homers, 105 runs batted in).